BIODIVERSITY RESEARCH An elevational shift of cryophilous bryophytes in the last century – an effect of climate warming? Ariel Bergamini 1 *, Stefan Ungricht 2 and Heike Hofmann 3 INTRODUCTION Since the early 20th century, global average surface temperatures have been increasing (IPCC, 2007). In Switzerland, the mean decadal temperature increase during the 20th century has been estimated at 0.135 °C (Rebetez & Reinhard, 2008), which is approximately twice the global rate (Jones & Moberg, 2003). In the last 30 years, the rate in Switzerland has even increased to 0.57 °C per decade (Rebetez & Reinhard, 2008). A relationship between climate warming and observed distribution shifts – both latitudinal (Hickling et al., 2006) and altitudinal (Wilson et al., 2005) – has been suspected for a 1 Swiss Federal Research Institute WSL, Biodiversity & Conservation Biology, Zu ¨rcherstrasse 111, CH-8903 Birmensdorf, 2 Swiss Federal Institute of Technology ETH, Earth Science Collections, Sonneggstrasse 5, CH-8092 Zu ¨rich, 3 National Inventory of Swiss Bryophytes NISM, Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, CH-8008 Zu ¨rich, Switzerland *Correspondence: Ariel Bergamini, Swiss Federal Research Institute WSL, Biodiversity & Conservation Biology, Zu ¨rcherstrasse 111, CH-8903 Birmensdorf, Switzerland. E-mail: ariel.bergamini@wsl.ch ABSTRACT Aim To investigate altitudinal range shifts of bryophytes in Switzerland by comparing recent altitudinal distributions with historical distributions derived from herbarium specimens. Location Switzerland, covering 41,285 km 2 in Central Europe. Methods We used a dataset of 8520 herbarium specimens of 61 bryophyte species and compared altitudinal data between the two periods 1880–1920 and 1980– 2005. The records we used were not specifically sampled for climatological analyses, but originate from non-systematic fieldwork by various collectors. Historical and recent records were distributed all over Switzerland with occurrences in all major biogeographical areas. To account for different sampling efforts in the two time periods, different subsampling procedures were applied. Results Overall, we found a significant mean increase in altitude of 89 ± 29 m which was mainly driven by the cryophilous species (+222 ± 50 m). The mean increase in altitude of cryophilous species corresponds to a decadal upward shift of 24 m. The upper range limit of cryophilous species also increased by 189 ± 55 m, but there was no effect on the lower range limit. For intermediate and thermophilous species neither mean, nor upper or lower range limits changed. However, the proportion of records of thermophilous to cryophilous species increased considerably at lower altitudes, but levelled off above approximately 1800 m. Main conclusions We conclude that cryophilous bryophytes are expanding their range to higher elevations in Switzerland and that at lower elevations, a slow extinction process is going on, probably as a result of climate warming trends. The observed decadal upward shifts of cryophilous species closely match those reported from vascular plants in Europe and those expected, given recent estimates of climate warming trends. We emphasize that herbaria provide valuable data that can be used to detect ongoing changes in the distribution of species. Keywords Altitudinal range displacement, elevational limits, extinction, herbarium specimens, historical records, liverworts and mosses. Diversity and Distributions, (Diversity Distrib.) (2009) 15, 871–879 DOI: 10.1111/j.1472-4642.2009.00595.x ª 2009 Blackwell Publishing Ltd www.blackwellpublishing.com/ddi 871